W211 Facelift - Need To Disconnect Auxiliary Battery Before Remving Xenon Ballasts / CUs

[pretzelmeister]

Hi All.
I have a Xenon low beam issue on passenger side. Have fitted new bulb, still no joy - ballast / control unit is suspect.
Plan to switch ballasts between sides.
In addition to disconnecting main battery, should I also disconnect auxiliary battery before doing the CU swap?
TIA,

 

[KillerHERTZ]

You shouldnt need to, but due to the possible high voltages used with the ballasts, I would disconnect everything and wait 20 mins before touching anything.

 

[Diesel Benz]

The facelift W211 does not have any aux battery (no SBC brakes, no stop/start).

 

[pretzelmeister]

Indeed - no aux battery - just pollen / cabin filter!
Good access to RHS / driver's (UK) side ballast from below.....
...but not so the other side. Air compressor in the way - which is easy enough to remove - but there is mounting plate / bracket for it which looks like will still be pretty obstructive and less easy to remove.
So will need to try the bumper off, headlight unit out approach. Hoping for dry weather on the weekend....
BTW, if I do have to go down the replacement xenon ballast route, does such a thing as a decent aftermarket (non-Hella, non-Mercedes) unit exist? If so, any recommendations please?